I was lucky enough to find a remaindered copy of this omnibus at a very low price, so bought it without previous experience of the author.
The first book, the Colour of Law, I found to be excellent. Gimenez successfully picked apart the façade that successful lawyers maintain with both wit and some vehemence, and drove his protagonist to make some hard choices. Readers familiar with To Kill A mockingbird will recognise a number of plot points and Gimenez himself acknowledges the book as an inspiration to both himself and his main character.
Abduction, on the other hand was a bit of a Curate's Egg: good in places. Much more serious in tone than the other book, it explores the search for a kidnapped child and the impact on the family as revelations about their respective backgrounds come to the fore. Unfortunately, to drive the plot along, Gimenez makes extensive use of coincidence and even throws in a bit of psychic mumbo jumbo for good measure. The Vietnam flashbacks are well handled, if predictable, and the action moves along at a good pace. That said, however, it's a much weaker effort than The Colour of Law and I doubt if I'd have been so keen to read the whole omnibus if this had been the first book in the collection.
Overall, call it 7.5/10, with most of the marks going to The Colour of Law.